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Saturnian storm goes wild

Saturn's northern storm marches through the planet's atmosphere in the top right of this false-color mosaic from NASA's Cassini spacecraft.

"Over the past year, a great disquiet has swept across the face of Saturn..." It sounds like the beginning of a science-fiction movie, but it's actually the latest missive from Carolyn Porco, head of the imaging team for the Cassini mission to Saturn. Today, Porco and her colleagues presented a visual chronicle of the largest Saturnian storm in more than a decade.

The storm was first noticed almost a year ago, as a spot near the line between day and night on the northern hemisphere. Since then, it's grown into a wide, bright band stretching around the entire planet.

"With a 200-day interval of intense, hissing convection, it holds the record as the longest-lasting Saturn-encircling storm ever," Porco writes. "And it has become the largest by far ever observed on the planet by an interplanetary spacecraft, giving us an unparalleled opportunity to study in great depth the subtle changes on the planet that preceded the storm's formatin and the mechanisms involved in its development."

The imaging team has bumped up the colors on a few of the images, like the one shown above, but the true-color images taken over the course of the past year tell a story that's just as dramatic.

NASA / JPL-Caltech / SSI

Images from Cassini show the evolution of a giant Saturnian storm over the course of months.

It's been 14 years and a month since Cassini was launched, and for seven and a half years it's been observing Saturn and many of its 60-plus moons. That puts Cassini right up there with the Mars rovers among NASA's most successful interplanetary missions. "And with any luck, there'll be a great deal more to come," Porco writes.